<a href="https://player.vimeo.com/video/147149584" class="wplightbox" data-autoopen="true" data-autoopendelay=1000 data-autoclose="true">Click to open a Vimeo video in a Lightbox</a>

The data tag data-autoopen="true" automatically opens the lightbox on page load, data-autoopendelay=1000 defines the open delay in milliseconds, data-autoclose="true" enables the auto close on video finish.

If you want to hide the Vimeo lightbox link, you can place the code into a hidden div, for example: